Battery charger



Feb. 9, 1943. J. c. KNIGHT 2,310,700

BATTERY CHARGER Filed Sept. 11, 1940 IJIJUUUU UUUUUUUUIJ DIJUUEIUUIJU 1mm TOR. .1015 C. KNIGHT. BX

H T TOR/VE Y.

Patented Feb. 9, 1943 uuirso STATES PATENT OFFICE 2,310,700 BATTERY CHARGER J oie 0. Knight, Long Beach, Calif. Application September 11, 1940, Serial No. 356,253

2 Claims.

This invention relates to a battery charger whereby a battery charging device is automatically operated to charge the battery when the charge in said battery drops to a predetermined level.

While I am familiar with the so-called trickle chargers, which are now on the market, these chargers introduce a charge into the battery continuously at given intervals. With my arrangement, the battery charger is actuated to charge the battery only when the charge in the battery drops to a predetermined level.

An object of my invention is to provide a novel battery charger in which a photo-electric cell is controlled to start and stop the battery charger.

A feature of my invention resides in the arrangement of a hydrometer float which controls a light beam directed on the photo-electric cell.

An advantage of my invention resides in the maintaining of a substantially full charge in the battery and without danger of overcharging the battery it this battery is not used for a, considerable period of time.

My invention is particularly useful in connection with emergency lighting, although it may be used in various other circumstances and conditions.

Other objects, advantages and features of invention may appear from the accompanying drawing, the subjoined detailed description, and the appended claims.

In the drawing:

Figure l is a side elevation of a battery with parts broken away to show interior construction, and including my novel battery charger.

Figure 2 is a wiring diagram of the battery charger and control therefor.

Referring more particularly to the drawing, the numeral I indicates a battery which is being used from time to time for various purposes and consequently the charge in this battery is being reduced. It is necessary then to keep this charge in the battery at substantially the maximum amount.

A vertical glass or transparent tube 2 is connected to the battery by means of upper and lower tubes 3 and 4. The electrolyte in the battery thus fills the tube 2. A hydrometer float 5 is positioned in the tube 2 and rises and falls in this tube as the charge in the battery I varies. All of this is usual and well-known. A small light 6 is mounted adjacent the tube 2 and the light from this bulb shines through the tube 2. When the hydrometer float 5 rises in the tube I due to a full charge in the battery, the light from the bulb 5 will be cut off. When the charge in the battery is reduced, the hydrometer 5 drops in the tube "2, permitting the light from the bulb 5 to pass through the tube. A photo-electric cell i is mounted adjacent the tube 2 and on the side opposite the bulb 5. The photo-electric cell '5 controls the battery charger 8 in substantially.

the following manner:

An outside source of alternating current of the usual ill) to volt type, shown at $3, feeds current to a transformer it. An amplifying tube ii and a relay are connected in a circuit with the transformer it, and also with the photo-electric cell i. This particular electrical circuit is usual and well-known, and the details of the circuit form no part or" this invention. Such a typical circuit is shown in Figure 2.

When the hydrometer float 5 drops in the tube 2, the lightrrom the bulb B will shine on the photo-electric cell '5, thus actuating this cell and in turn actuating the relay l2. When the relay i2 is thus actuated, the switch contact i3 is closed, thus throwing into the circuit the charging transformer 44 through the leads !5 and iii. A rectifying tube i1 is arranged in the circuit with the transformer l4, substantially as shown in Figure 2, thus introducing a six volt A. C. charge to the battery l. I'he battery continues to be charged until the hydrometer float 5 rises in the tube 2, shutting off the light to the photo=- electric cell i. releases the relay l2 and the charging transformer I4 is cut out of the circuit.

As one example for the use of the battery l, in theatres when the main current supply sometimes goes ofl, batteries are used for emergency lighting of exit lights, shOWn at i8. If the current supply 9 is out off, the relay I9 is not energized, thus closing the switch contact 20, and

current then flows from the battery I to the lights 18.

The battery I can be used under any circumstances, and I do not wish to limit myself to this emergency lighting arrangement, shown in Figure 2.

Having described my invention, I claim:

1. A system for controlling a battery charger comprising a wet battery, a charging means electrically connected to the battery, a photo-electric cell, means operable by'the photo-electric cell and controlling the operation of the charger, a vertical glass tube, said tube being connected at the top and bottom to the electrolyte in the battery, a hydr'ometer float in said tube, said photophoto-electric cell, said relay being electrically connected to the charging transformer and adapted and arranged to direct the outside source of electrical power to the charging transformer when said relay is actuated, a trans parent tube connected to the electrolyte in the battery, a hydrometer float in the tube, a light source on one side of said tube, said photo-electric cell being arranged on the other side of the tube, the hydrometer float controlling the beam or light from the light source onto the photoelectric cell. 1

JOE C. KNIGH'I. 

